An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material such as straw from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
During the process of harvesting in a combine, the desired grain is gathered and saved while crop material other than the desired grain is expelled from the combine. The non-grain crop material or crop residue is usually derived from two areas in the combine, the threshing rotor and the cleaning system. The material expelled from the threshing rotor is generally referred to as straw and includes much of the larger plant material such as stalks, stems, cobbs leaves and the like as well as foreign or non-crop material. The material expelled from the cleaning system is generally referred to as chaff and includes much of the finer plant material residue, such as pods, husk fragments and particulates. The combined flows of crop residue to be expelled from the combine can be dealt with in several ways; however, the processes for redepositing the residue material back into the field can be categorized generally as either windrowing or spreading.
In a windrowing process, the crop residue is deposited onto the harvested crop stubble in a continuous narrow stream or windrow, which is narrower than the harvested swath width. Accumulated in this manner, the windrowed residue material can be picked up easily for baling or other subsequent processing or use.
In a spreading process, a mechanical device distributes the straw and/or chaff evenly across the extent of the combine header cutting width. The material to be spread is usually chopped to a short length so that after spreading the material will break down quickly to add nutrients to the soil and/or to be sufficiently small so as to not interfere with subsequent tilling or seeding operations.
To windrow the crop residue, the residue is directed to a windrow assembly held at the rear of the vehicle. The windrow assembly includes a chute the residue travels along and vanes or a different mechanism for controlling the width of the windrow that is left on the field.
One particular problem that occurs when windrowing crop residue is hair pinning at the leading edge of the windrow chute. Since the leading edge must be properly spaced to protect the windrowed residue from being disturbed by the wind generated by the spreader, catch all straw coming from the threshing rotor and not catch chaff coming from the cleaning system, some of the crop residue passing the leading edge will tend to accumulate on the leading edge. Once some crop residue accumulates on the leading edge, the accumulation at the leading edge can quickly build up and disrupt operation of the combine.
What is needed in the art is a windrow assembly for an agricultural vehicle which is less prone to material accumulation at the leading edge.